1. Field of the Invention
This invention relates to substrates for paperboard packaging having a press-applied barrier coating. Such structures of this type, generally, reduce the edgewick in the paperboard package such that catastrophic failure of the paperboard package is substantially reduced.
2. Description of the Related Art
It is known, in paperboard packaging, to produce a paperboard carton with a press-applied barrier coating on the nonclay-coated side. Due to the lack of hold-out, severe pin-holing may be observed. On a clay-coated side, a nearly pin-hole free, press-applied film may be achieved. However, during folding and scoring operations, pin holes develop in the press-applied barrier film at corners and seams and may result in the food product attacking the paperboard layer resulting in catastrophic failure. Also, if a clay-coated surface is required beneath the press-applied film, this may require exterior printing on a nonclay-coated side if C1S (coated one side) board is used. This may dramatically reduce the print quality of the package. Consequently, a more advantageous substrate, then, would be presented if such edgewicking could be substantially reduced.
It is also known, in paper coating systems, to make use of styrene maleic anhydride as a coating binder for mineral coated paper. Exemplary of such prior art is U.S. Pat. No. 2,577,624 ('624) to George E. Niles, entitled "Mineral-Coated Paper and Process of Producing Same". While the styrene maleic anhydride is used as a coating binder for the mineral coated paper, its presence in the coating does not contribute to any edgewick resistance of the substrate. Thus, it would not adequately prevent edgewicking. Consequently, a still further advantageous substrate, then, would be presented if a suitable sizing compound were employed that prevented edgewicking.
It is apparent from the above that there exists a need in the art for a substrate for paperboard packaging which is capable of reduced edgewicking and Cobb measurements, but which at the same time is able to have a press-applied barrier placed on one side of the paperboard. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.